PTL 1 below describes a known structure of a cutting tool for turning, such as cutting off or grooving.
In the structure described in PTL 1, a recess having a curved groove surface is formed in a rake face in a central region in a width direction, and the recess serves as a breaker for curling chips. The recess has a width that gradually decreases with increasing distance from the cutting edge, so that the chips receive not only a curling force but also a bending force in the width direction.